Nuclear radiation particle power converter

ABSTRACT

Various embodiments of a nuclear radiation particle power converter and method of forming such power converter are disclosed. In one or more embodiments, the power converter can include first and second electrodes, a three-dimensional current collector disposed between the first and second electrodes and electrically coupled to the first electrode, and a charge carrier separator disposed on at least a portion of a surface of the three-dimensional current collector. The power converter can also include a hole conductor layer disposed on at least a portion of the charge carrier separator and electrically coupled to the second electrode, and nuclear radiation-emitting material disposed such that at least one nuclear radiation particle emitted by the nuclear radiation-emitting material is incident upon the charge carrier separator.

This application is a continuation of U.S. patent application Ser. No.16/155,145, filed Oct. 9, 2018, which is a divisional of U.S. patentapplication Ser. No. 14/666,890, filed on Mar. 24, 2015, now U.S. Pat.No. 10,096,393, which claims the benefit of the filing date of U.S.Provisional Application No. 61/972,551, filed Mar. 31, 2014, the contentof which are incorporated by reference in their entireties.

BACKGROUND

Radiation particle power converters can convert energy from aradioactive source that emits high-energy electrons, e.g., betaparticles, into electrical energy. The power converter can convert theenergy of the high-energy electrons to electrical energy, i.e., current,by collecting electron-hole pairs that are formed by the high-energyelectrons that are incident upon a semiconductor material of the powerconverter.

One such power converter includes a radiation-emitting radioisotope anda plurality of semiconductor substrates. Each of the plurality ofsemiconductor substrates includes a junction for converting nuclearradiation particles to electrical energy, e.g., a p-n junction. Thejunction collects electron-hole pairs that are created within thesemiconductor material as a result of interaction with the nuclearradiation particles. Specifically, when a radiation particle ofsufficient energy impacts the semiconductor material, electrons in thesemiconductor material are excited into a conduction band of thesemiconductor material, thereby creating electron-hole pairs. Electronsformed on an n side of a p-n junction are generally prevented fromcrossing the p-n junction due to the electric field that is created in adepletion zone, while the corresponding holes are swept across the p-njunction by the electric field. Electrons formed on the p side of thep-n junction are swept across the junction by the electric field whilethe corresponding holes are prevented from crossing the junction by theelectric field. When the semiconductor material is connected to a load,electrons formed on the n side of the junction or are swept across thejunction from the p side are further swept via an anode through acircuit connected to the power converter. The electrons that flowthrough the circuit then flow into the p side via a cathode, where theycan recombine with holes formed as part of the original electron-holepairs.

SUMMARY

In general, the present disclosure provides several embodiments of anuclear radiation particle power converter.

In one aspect, the present disclosure provides one embodiment of a powerconverter that includes first and second electrodes; a three-dimensionalcurrent collector disposed between the first and second electrodes andelectrically coupled to the first electrode; and a charge carrierseparator disposed on at least a portion of a surface of thethree-dimensional current collector. The power converter furtherincludes a hole conductor layer disposed on at least a portion of thecharge carrier separator and electrically coupled to the secondelectrode; and nuclear radiation-emitting material disposed such that atleast one nuclear radiation particle emitted by the nuclearradiation-emitting material is incident upon the charge carrierseparator.

In another aspect, the present disclosure provides one embodiment of amethod that includes forming a three-dimensional current collectorbetween first and second electrodes, where the three-dimensional currentcollector is electrically coupled to the first electrode; forming acharge carrier separator on at least a portion of a surface of thethree-dimensional current collector; and forming a hole conductor layeron at least a portion of the charge carrier separator, where the holeconductor layer is electrically coupled to the second electrode. Themethod further includes forming nuclear radiation-emitting materialproximate the charge carrier separator such that at least one nuclearradiation particle emitted by the nuclear radiation-emitting material isincident upon the charge carrier separator.

These and other aspects of the present disclosure will be apparent fromthe detailed description below. In no event, however, should the abovesummaries be construed as limitations on the claimed subject matter,which subject matter is defined solely by the attached claims, as may beamended during prosecution.

BRIEF DESCRIPTION OF THE DRAWINGS

Throughout the specification, reference is made to the appendeddrawings, where like reference numerals designate like elements, andwherein:

FIG. 1A is a schematic cross-section view of one embodiment of a powerconverter.

FIG. 1B is a schematic cross-section view of a portion of the powerconverter of FIG. 1A.

FIG. 2 is a schematic cross-section view of a portion of anotherembodiment of a power converter.

FIG. 3 is a schematic cross-section view of a portion of anotherembodiment of a power converter.

FIG. 4 is a schematic cross-section view of a portion of anotherembodiment of a power converter.

FIG. 5 is a schematic cross-section view of a portion of anotherembodiment of a power converter.

FIG. 6 is a schematic cross-section view of a portion of anotherembodiment of a power converter.

FIG. 7 is a schematic cross-section view of one embodiment of animplantable medical device that includes a power converter.

DETAILED DESCRIPTION

In general, the present disclosure provides several embodiments of anuclear radiation particle power converter. In one or more embodiments,the power converter can include nuclear radiation-emitting material thatemits nuclear radiation particles whose energy can be converted toelectrical energy, i.e., current, by the power converter. This nuclearradiation-emitting material can, e.g., emit alpha particles (a nuclearparticle that includes two protons and two neutrons, e.g., a nucleus ofa helium atom) via alpha decay, or beta particles (a high-energyelectron) via beta decay. Although the power converters described in thepresent disclosure may be configured to convert any suitable nuclearradiation particle to electrical energy, the disclosure will focus onpower converters for converting energy from beta particles intoelectrical energy, generally referred to as “betavoltaic powerconverters.” Energy from the beta particles may be converted by thepower converter using a charge carrier separator (e.g., quantum dots)that in one or more embodiments facilitates the separation ofelectron-hole pairs created by high energy electrons that are generatedfrom the nuclear radiation-emitting material that decays by betaparticle emission.

In one or more embodiments, the power converter can include a chargecarrier separator disposed on at least a portion of a surface of athree-dimensional current collector that is disposed between first andsecond electrodes. A hole conductor layer can be disposed on at least aportion of the charge carrier separator. And in one or more embodiments,nuclear radiation-emitting material can be disposed such that at leastone nuclear radiation particle emitted by the nuclear radiation-emittingmaterial is incident upon the charge carrier separator.

For example, FIGS. 1A-B are schematic cross-section views of oneembodiment of a power converter 10, where FIG. 1B is an enlarged view ofa portion of the power converter 10 of FIG. 1A. The power converter 10includes a first electrode 12 and a second electrode 20. Athree-dimensional current collector 30 is disposed between the first andsecond electrodes 12, 20 and, in one or more embodiments, electricallycoupled to the first electrode. The power converter 10 can also includea charge carrier separator 40 (FIG. 1B) disposed, in one or moreembodiments, on at least a portion of a surface 32 of thethree-dimensional current collector 30. A hole conductor layer 50 can bedisposed, e.g., on at least a portion of the charge carrier separator40. In one or more embodiments, the hole conductor layer 50 iselectrically coupled to the second electrode 20.

Power converter 10 can also include nuclear radiation-emitting material60 (FIG. 1B). In one or more embodiments, the nuclear radiation-emittingmaterial 60 can be disposed in any suitable location relative to thecharge carrier separator 40 such that at least one nuclear radiationparticle emitted by the nuclear radiation-emitting material is incidentupon the charge carrier separator. For example, in one or moreembodiments, the nuclear radiation material 60 can be disposed within atleast one of the three-dimensional current collector 30, charge carrierseparator 40, and the hole conductor layer 50. In one or moreembodiments, the nuclear radiation material 60 can be formed such that acounter electrode 70 is positioned between the nuclear radiationmaterial and the hole conductor layer 50 as is further described herein.

The first and second electrodes 12, 20 can take any suitable shape orshapes and include any suitable materials, e.g., metals, conductivepolymers, other suitable electrical conductors, or combinations thereof.In one or more embodiments, the materials for the first electrode 12 andthe three-dimensional current collector 30 can be selected such that thework functions of the materials prevent schottky barriersemiconductor/conductor interfaces from being formed. In one or moreembodiments, the materials of the first electrode 12 and thethree-dimensional current collector 30 can be selected and configuredsuch that they form a schottky barrier or an ohmic contact. In one ormore embodiments, the materials for the second electrode 20 and the holeconductor layer 50 and/or the counter electrode 70 can be selected suchthat the work functions of the materials prevent schottky barriersemiconductor/conductor interfaces from being formed. In one or moreembodiments, the materials for the second electrode 20 and the holeconductor layer 50 and/or the counter electrode 70 can be selected andconfigured such that they form a schottky barrier or alternately form anohmic contact.

In one or more embodiments, the first and second electrodes 12, 20 canelectrically couple the power converter 10 to other devices using anysuitable techniques. Further, either of the first or second electrodes12, 20 can be positive or negative depending upon the application inwhich the power converter 10 is utilized.

Disposed between the first and second electrodes 12, 20 is thethree-dimensional current collector 30. As used herein, athree-dimensional current collector is a structure or device thatincludes one or more surfaces that provide the collector with an extentin three dimensions and that is configured to receive or transmit acurrent on or through the one or more surfaces of the collector. In oneor more embodiments, the three-dimensional current collector 30 can beconstructed such that it provides a heterostructure with the chargecarrier separator 40.

In one or more embodiments, the three-dimensional current collector 30is electrically coupled to the first electrode 12. In one or moreembodiments, the three-dimensional current collector 30 is electricallycoupled to the second electrode 20. In one or more embodiments, thethree-dimensional current collector 30 can be formed on the firstelectrode 12. In one or more embodiments, the collector 30 can be formedon the second electrode 20. In one or more embodiments, one or moreintervening layers can be disposed between the three-dimensional currentcollector 30 and one or both of the first and second electrodes, 12, 20that provides added functionality, e.g., a conductive layer, an adhesionlayer, etc.

The three-dimensional current collector 30 can include any suitablematerial or materials. In one or more embodiments, the collector 30 caninclude a porous material. Further, in one or more embodiments, thecollector 30 can include a high bandgap semiconductor material, e.g.,TiO2, SnO2, ZnO, WO3, Nb2O5, Ta2O5, BaTiO3, SrTiO3, ZnTiO3, CuTiO3, andcombinations thereof. In one or more embodiments, the collector 30 caninclude graphite, graphene, C60, C70 and combinations thereof. Further,in one or more embodiments, the collector 30 can include a poroussintered TiO2 material, a porous Ti/TiO2 material, etc.

The three-dimensional current collector 30 can take any suitable shapeor shapes. In one or more embodiments, the collector 30 can includenanorods, nanotubes, nanowires, nanocrystalline structures, metal foam,graphene foam, and combinations thereof. In one or more embodiments, thecollector 30 can include a lithographically-patterned structure or otherordered structure such as those that can be manufactured using, e.g., 3Dprinting techniques. And the surface 32 of the collector 30 can take anysuitable shape or shapes. In general, the three-dimensional currentcollector 30 can, in one or more embodiments, maximize a surface area ofsurface 32 for any given volume.

The power converter 10 can also include a charge carrier separator 40.The separator 40 can be disposed in any suitable location. For example,in the embodiment illustrated in FIGS. 1A-B, the separator 40 isdisposed on at least a portion of the surface 32 of thethree-dimensional current collector 30. The charge carrier separator 40can be disposed on any suitable portion of the surface 32 of thethree-dimensional current collector, e.g., the entire surface 32.

In one or more embodiments, the charge carrier separator 40 can bedisposed within the hole conductor layer 50 such that it provides athree-dimensional structure but still is in contact with thethree-dimensional current collector 30. In one or more embodiments, thecharge carrier separator 40 and the three-dimensional current collector30 can form a heterostructure.

The charge carrier separator 40 can include any suitable material ormaterials. In one or more embodiments, the separator 40 can include anoxide. In one or more embodiments, the separator 40 can be an oxide ofthe material used to form the three-dimensional current collector 30,e.g., TiO2. In one or more embodiments, the charge carrier separator 40can include nanocrystals. As used herein, the term “nanocrystal” refersto nanostructures that are substantially monocrystalline. A nanocrystalhas at least one region or characteristic dimension with a dimension ofless than about 500 nm, and down to on the order of less than about 1nm. The terms “nanocrystal,” “nanodot,” “dot,” and “quantum dot” arereadily understood by the ordinarily skilled artisan to represent likestructures and are used herein interchangeably. The present disclosurealso encompasses the use of polycrystalline or amorphous nanocrystals.Typically, the region of characteristic dimension will be along thesmallest axis of the structure. Nanocrystals can be substantiallyhomogenous in material properties, or in some embodiments, can beheterogeneous.

The nanocrystals can be produced using any suitable technique ortechniques. The nanocrystals for use in the present disclosure can alsoinclude any suitable material or materials, including an inorganicmaterial, and more suitably an inorganic conductive or semiconductivematerial. Suitable semiconductor materials can include any type ofsemiconductor, including group II-VI, group III-V, group IV-VI and groupIV semiconductors. Suitable semiconductor materials can include, but arenot limited to, Si, Ge, Sn, Se, Te, B, C (including diamond), P, BN, BP,BAs, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb,AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, ZnO, ZnS, ZnSe, ZnTe, CdS,CdSe, CdTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS, MgSe, GeS, GeSe,GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCl, CuBr, CuI,Si3N4, Ge3N4, Al2O3, (Al, Ga, In)2 (S, Se, Te)3, Al2CO, and combinationsthereof.

In one or more embodiments, the semiconductor nanocrystals can include adopant such as a p-type dopant or an n-type dopant. The nanocrystalsuseful in the present disclosure can also include II-VI or III-Vsemiconductors. Examples of II-VI or III-V semiconductor nanocrystalsinclude any combination of an element from Group II, such as Zn, Cd andHg, with any element from Group VI, such as S, Se, Te, Po, of thePeriodic Table; and any combination of an element from Group III, suchas B, Al, Ga, In, and Tl, with any element from Group V, such as N, P,As, Sb and Bi, of the Periodic Table.

In one or more embodiments, the nanocrystals can include core-shellstructures that are obtained by adding organometallic precursorscontaining the shell materials to a reaction mixture containing the corenanocrystal. In this case, rather than a nucleation-event followed bygrowth, the cores act as the nuclei, and the shells grow from theirsurfaces. The temperature of the reaction is kept low to favor theaddition of shell material monomers to the core surface, whilepreventing independent nucleation of nanocrystals of the shellmaterials. Surfactants in the reaction mixture are present to direct thecontrolled growth of shell material and ensure solubility. A uniform andepitaxially grown shell is obtained when there is a low lattice mismatchbetween the two materials.

Exemplary materials for preparing core-shell nanocrystals can include,but are not limited to, Si, Ge, Sn, Se, Te, B, C (including diamond), P,Co, Au, BN, BP, BAs, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN,InP, InAs, InSb, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, ZnO, ZnS,ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS,MgSe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCl,CuBr, CuI, Si3N4, Ge3N4, A1203, (Al, Ga, In)2 (S, Se, Te)3, Al2CO, andcombinations thereof. Exemplary core-shell luminescent nanocrystalsinclude, but are not limited to, (represented as Core/Shell), CdSe/ZnS,InP/ZnS, PbSe/PbS, CdSe/CdS, CdTe/CdS, CdTe/ZnS, as well as others.

In one or more embodiments, the nanocrystals can include functionalizedligands to promote adhesion to the surface 32 of current collector 30 orto additional material of the charge carrier separator 40 as is furtherdescribed herein. The ligands may also be used to facilitate bonding tothe nuclear radiation-emitting material 60 as is also further describedherein. The ligands may also facilitate charge transfer from thenanocrystals to at least one of the charge carrier separator 40, thecurrent collector 30, and the hole conductor layer 50.

In one or more embodiments, the charge carrier separator 40 can be alayer that is formed or deposited onto the at least a portion of thesurface 32 of three-dimensional current collector 30. In one or moreembodiments, the charge carrier separator 40 can include two or morelayers.

In one or more embodiments, the charge carrier separator 40 can includeother types of structures, e.g., quantum wells, PN junctions, PINjunctions, schottky junctions, and perovskite structures. And in one ormore embodiments, the charge carrier separator 40 can include two ormore types of materials, e.g., an oxide layer combined withnanocrystals, two or more different types of nanocrystals, one or morequantum wells combined with nanocrystals, etc., as is further describedherein.

The power converter 10 can also include the hole conductor layer 50. Inone or more embodiments, the hole conductor layer 50 is disposed on atleast a portion of the charge carrier separator 40. Further, in one ormore embodiments, the hole conductor layer 50 is disposed on at least aportion of the surface 32 of the three-dimensional current collector 30.And in one or more embodiments, the hole conductor layer 50 can bedisposed on at least a portion of the charge carrier separator 40 and atleast a portion of the surface 32 of the three-dimensional currentcollector 30. In one or more embodiments, the hole conductor layer 50can be disposed on at least a portion of the surface 32 of thethree-dimensional current collector 30, and the charge carrier separator40 can be disposed within the hole conductor layer such that it iselectrically coupled with the current collector 30. In one or moreembodiments, the hole conductor layer 50 is electrically coupled to thesecond electrode 20 to provide an electrical pathway for one or both ofthe electrons and holes emitted by the charge carrier separator 40.

The hole conductor layer 50 can include any suitable material ormaterials. For example, in one or more embodiments, the hole conductorlayer 50 can include any suitable p-type semiconductor material, e.g.,CsSnI3, ZnO, CuSCN, doped or undoped graphene, hole conducting holetransport medium (i.e., hole conductor, hole transport medium) such asPTAA or PEDOT, and liquid redox shuttles such as I-/I3-. The term“p-type” or “p-doped” as used in this disclosure refer to asemiconductor material that includes a dopant that provides for excessholes to act as positive, or “p-type,” mobile charge carriers. In oneexample, a p-type dopant can accept an electron from the semiconductormaterial. The p-type semiconductor material may also be made ofintrinsic p-type material.

Further, the terms “n-doped” or “n-type” as they are used in thisdisclosure refer to a semiconductor material that includes a dopant thatprovides for excess electrons to act as negative, or “n-type,” mobilecharge carriers. In one example, an n-type dopant can donate one or morevalence electrons to a semiconductor material. The n-type semiconductormaterial may also be made of intrinsic n-type material.

The power converter 10 can also include nuclear radiation-emittingmaterial 60. The material 60 can be disposed in any suitable location.For example, in one or more embodiments, the material 60 can be disposedproximate the charge carrier separator 40 to minimize losses in particleenergy. As used herein, the phrase “proximate the charge carrierseparator” means that the nuclear radiation-emitting material isdisposed such that at least one nuclear radiation particle emitted bythe nuclear radiation-emitting material is incident upon the chargecarrier separator. For example, in one or more embodiments, the material60 can be disposed within at least one of the three-dimensional currentcollector 30, charge carrier separator 40, and hole conductor layer 50(as illustrated in FIG. 1B). In one or more alternative embodiments, thematerial 60 can be disposed such that a counter electrode 70 is betweenthe material 60 and the charge carrier separator 40 (see, e.g., powerconverter 600 of FIG. 6 ).

The nuclear radiation-emitting material 60 can include any suitablematerial or materials. In one or more embodiments, the nuclearradiation-emitting material 60 can include a plurality ofradiation-emitting radioisotopes, e.g., tritium 3H, 60Co, 63Ni, 90Sr,99Tc, 127Cs and combinations thereof. And the material 60 can emit anysuitable type of particles, e.g., alpha, beta, gamma, x-ray, etc.

In one or more embodiments, the power converter 10 can include optionalcounter electrode 70 disposed between the hole conductor layer 50 andsecond electrode 20. The counter electrode 70 can be electricallycoupled to the hole conductor layer 50. In one or more embodiments, thecounter electrode 70 can electrically couple the hole conductor layer 50and the second electrode 20. In one or more embodiments, the counterelectrode 70 can be in contact with the second electrode 20. In one ormore embodiments, the counter electrode can be electrically coupled tothe second electrode 20 through a conductive adhesive 72 (FIG. 1A).Further, in one or more embodiments, the counter electrode 70 can beelectrically coupled to the hole conductor layer 50 through a conductiveadhesive (not shown). And in one or more embodiments, the counterelectrode 70 can serve as the second electrode, thereby replacing secondelectrode 20.

The counter electrode 70 can include any suitable material or materials,e.g., Au, Pt, graphene, a metallic material, a conducting polymer, asemiconductor, or combinations thereof.

The power converter 10 can include any other suitable layer or layers.For example, in one or more embodiments, the power converter 10 caninclude one or more absorption layers for absorbing nuclear radiationparticles that are emitted by the nuclear radiation-emitting material 60to prevent the release of nuclear radiation particles from the powerconverter. Such one or more absorbing layers may also absorbbremsstrahlung (x-rays) resulting from the deceleration of nuclearradiation particles emitted by the nuclear radiation-emitting material60.

While not wishing to be bound by any particular theory, the powerconverter 10 can provide a current to a device or system that iselectrically coupled to the converter by converting energy fromradioactive decay of the nuclear radiation-emitting material 60 intoelectrical energy. For example, in reference to FIG. 1B, the nuclearradiation-emitting material 60 can emit one or more nuclear radiationparticles 62, e.g., an electron, along with an antineutrino 64 as thematerial 60 decays. The particle 62 can generate electron/hole pairs44/46 in the charge carrier separator 40 through, e.g., impactionization. One or more liberated electrons 44 or excitons can beinjected into a conduction band of the three-dimensional currentcollector 30. The collector 30 can direct these liberated electrons 44to the first electrode 12 (FIG. 1A) before the liberated electrons 44can recombine with their associated holes 46. The hole conductor layer50 can fill the holes 46, i.e., electron vacancies, in the chargecarrier separator 40 by replenishing the separator 40 with electrons.This replenishing of electrons can aid in preventing recombination ofelectron-hole pairs 44/46 before the liberated electrons 44 can becollected by the collector 30. In one or more embodiments, the electrons44 can be absorbed by the three-dimensional current collector 30 morequickly than the electrons can recombine with the associated holes 46,thereby also helping to prevent the electron-hole pairs fromrecombining.

As mentioned herein, the power converters of the present disclosure caninclude any suitable material or combination of materials for the chargecarrier separator. For example, FIG. 2 is a schematic cross-section viewof a portion of one of embodiment of a power converter 200. The powerconverter 200 is similar in many aspects to power converter 10illustrated in FIGS. 1A-B. All of the design considerations andpossibilities regarding the power converter 10 of FIGS. 1A-B applyequally to the power converter 200 of FIG. 2 .

One difference is that power converter 200 includes a charge carrierseparator 240 that includes a first material 242 disposed on at least aportion of a surface 232 of a three-dimensional current collector 230,and a second material 244. In the embodiment illustrated in FIG. 2 , thesecond material 244 is disposed on at least a portion of the firstmaterial 242. In one or more embodiments, the second material 244 can bedisposed within the first material 242, or spaced apart from the firstmaterial 242.

Charge carrier separator 240 can include any suitable material orcombination of materials. For example, in one or more embodiments, thefirst material 242 can include an oxide, e.g., an oxide of the materialutilized for the three-dimensional current collector 230, and the secondmaterial 244 can include quantum dots as described herein.

While not wishing to be bound by any particular theory, the powerconverter 200 can convert energy from nuclear radiation-emittingmaterial 260 into electrical energy by, e.g., impact ionization. Forexample, nuclear radiation-emitting material 260 can emit nuclearradiation particle 262 (e.g., an electron) and an antineutrino 264. Theparticle 262 is incident upon at least one of the first material 242 andthe second material 244 of the charge carrier separator 240. The impactof the particle 262 on one or both of materials 242, 244 can cause theformation of at least one electron-hole pair 246/248. The electrons 246from the pairs 246/248 can be directed by the three-dimensional currentcollector 230 to an electrode (not shown) as is further describedherein.

As mentioned herein, the power converters of the present disclosure caninclude nuclear radiation-emitting material that can be disposed in anysuitable location such that at least one nuclear radiation particleemitted by the nuclear radiation-emitting material is incident upon acharge carrier separator. For example, FIG. 3 is a schematiccross-section view of a portion of another embodiment of a powerconverter 300. All of the design considerations and possibilitiesregarding the power converters 10 and 200 of FIGS. 1A-B and FIG. 2 applyequally to the power converter 300 of FIG. 3 . One difference is thatpower converter 300 includes nuclear radiation-emitting material 360disposed in three-dimensional current collector 330. Any suitabletechnique or combination of techniques can be utilized to providenuclear radiation-emitting material 360 within three-dimensional currentcollector 330. The nuclear radiation-emitting material 360 is disposedsuch that at least one nuclear radiation particle emitted by the nuclearradiation-emitting material 360 is incident upon at least one of firstmaterial 342 and second material 344 of charge carrier separator 340.

Further, in one or more embodiments, nuclear radiation-emitting materialcan be disposed within charge carrier separator material. For example,FIG. 4 is a schematic cross-section view of a portion of a powerconverter 400. All of the design considerations and possibilitiesregarding the power converters 10 and 200 as illustrated in FIGS. 1A-Band FIG. 2 apply equally to the power converter 400 of FIG. 4 . Asillustrated in FIG. 4 , nuclear radiation emitting material 460 isdisposed within second material 444 of charge carrier separator 440. Anysuitable technique or combination of techniques can be utilized todispose nuclear radiation-emitting material within second material 444.As previously described herein, nuclear radiation-emitting material 460is disposed within second material 444 such that at least one nuclearradiation particle emitted by the nuclear radiation-emitting material isincident upon at least one of first material 442 and second material 444of the charge carrier separator 440. In one or more embodiments, thecharge carrier separator 440 can be disposed on at least a portion of asurface of three-dimensional current collector 430.

Nuclear radiation-emitting material can also be disposed within acounter electrode. For example, FIG. 5 is a schematic cross-section viewof a portion of a power converter 500. The power converter 500 caninclude any suitable power converter, e.g., power converters 10 and 200.All of the design considerations and possibilities regarding powerconverters 10 and 200 of FIGS. 1A-B and FIG. 2 apply equally to powerconverter 500 of FIG. 5 . As illustrated in FIG. 5 , nuclearradiation-emitting material 560 is disposed within counter electrode 570such that at least one nuclear radiation particle emitted by the nuclearradiation-emitting material is incident upon at least one of firstmaterial 542 and second material 544 of charge carrier separator 540.Nuclear radiation-emitting material 560 can be disposed within counterelectrode 570 using any suitable technique or combination of techniques.In one or more embodiments, the charge carrier separator 540 can bedisposed on at least a portion of a surface of three-dimensional currentcollector 530.

Nuclear radiation-emitting material of the power converters describedherein can also be disposed such that a counter electrode is between thenuclear radiation-emitting material and the charge carrier separator.For example, FIG. 6 is a schematic cross-section view of a portion of apower converter 600. All of the design considerations and possibilitiesregarding the power converters 10 and 200 as illustrated in FIGS. 1A-Band FIG. 2 apply equally to power converter 600 of FIG. 6 . Asillustrated in FIG. 6 , nuclear radiation-emitting material 660 isdisposed in matrix 680 adjacent counter electrode 670. The nuclearradiation-emitting material 660 is disposed such that the counterelectrode 670 is between the nuclear radiation-emitting material and acharge carrier separator 640. The nuclear radiation-emitting material660 is disposed such that at least one nuclear radiation particleemitted by the nuclear radiation-emitting material is incident upon atleast one of first material 642 and second material 644 of the chargecarrier separator 640. The nuclear radiation-emitting material 660 andmatrix 680 can be disposed on the counter electrode 670. Alternatively,one or more intervening layers can be disposed between the nuclearradiation-emitting material 660 and matrix 680, and the counterelectrode 670. The matrix 680 can include any suitable material ormaterials, e.g., polymers such as paraffin, liquids such as water,solids such as metals and oxides, etc.

Any suitable technique or combination of techniques can be utilized toproduce the power converters described herein. Referring to FIGS. 1A-B,the three-dimensional current collector 30, in one or more embodiments,can be formed between the first and second electrodes 12, 20. Thecollector 30 can be formed using any suitable technique or combinationof techniques, e.g., sintering, pressing, electrophoresis, anodicgrowth, cathodic reduction, etching, photolithography, 3D printing, orcombinations thereof. As mentioned herein, the collector 30 can beformed on either of the first and second electrodes 12, 20. In one ormore embodiments, the three-dimensional current collector 30 iselectrically coupled to the first electrode 12.

The charge carrier separator 40 can be formed on at least a portion ofthe surface 32 of the three-dimensional current collector 30 using anysuitable technique or combination of techniques, e.g., anodization, dropcoating, atomic layer deposition (ALD), sequential ionic layeradsorption, reaction (SILAR), chemical bath deposition (CBD) orcombinations thereof. The three-dimensional current collector 30 and thecharge carrier separator 40 can form a heterostructure.

The hole conductor layer 50 can be formed on at least a portion of thecharge carrier separator 40. In one or more embodiments, the holeconductor layer 50 is formed using any suitable technique or combinationof techniques, e.g., drop coating, atomic layer deposition (ALD),sequential ionic layer adsorption and reaction (SILAR), chemical bathdeposition (CBD) or combinations thereof.

The nuclear radiation-emitting material 60 can be formed proximate thecharge carrier separator 40. In one or more embodiments, the nuclearradiation-emitting material 60 can be formed within or attached to atleast one of the three-dimensional current collector 30, the chargecarrier separator 40, and the hole conductor layer 50 using any suitabletechnique or combination of techniques, e.g., exposure to a gaseous formof the material 60 (e.g., tritium gas) under pressure and/or heat,electroplating, synthesis, or combinations thereof. In one or moreembodiments, the nuclear radiation-emitting material 60 can be formedwithin the three-dimensional current collector 30 by depositingtritiated paraffin wax onto the current collector.

In one or more embodiments, the optional counter electrode 70 can beformed between the hole conductor layer 50 and the second electrode 20such that the counter electrode electrically couples the hole conductorlayer 50 and the second electrode 20. Any suitable technique orcombination of techniques can be utilized to form the counter electrode70, e.g., drop coating (if liquid), atomic layer deposition (ALD), etc.In one or more embodiments, where the nuclear radiation-emittingmaterial 60 is formed such that the counter electrode 70 is between thematerial 60 and the charge carrier separator 40, the material can beformed, e.g., on the counter electrode using any suitable technique orcombination of techniques. For example, in one or more embodiments, thenuclear radiation-emitting material 60 can be formed on the counterelectrode 70 by depositing tritiated paraffin wax onto the counterelectrode.

The various elements of the power converter can be formed in anysuitable order. For example, in one or more embodiments, the counterelectrode 70 can be formed first, followed by the hole conductor layer50, the charge separator 40, current collector 30, and the first andsecond electrodes 12, 20. In one or more embodiments, it may beadvantageous to dispose the nuclear radiation-emitting material 60 inthe desired location at the end of the process to help prevent thematerial 60 from degrading other elements of the power converter.

The various embodiments of power converters described herein can beutilized as a current source for any suitable devices or systems. Forexample, FIG. 7 is a schematic cross-section of one embodiment of animplantable medical device system 700 that includes a power converter710 and an implantable medical device 714. The power converter 710 caninclude any suitable power converter described herein, e.g., powerconverter 10 of FIGS. 1A-B. The implantable medical device 714 caninclude any suitable medical device, e.g., electrocardiogram (ECG)monitors, sensors (such as glucose, pressure), implantable pulsegenerators (IPGs) (e.g., pacemakers), implantable cardioverterdefibrillators (ICDs), etc. Although not shown, the power convertor 710can be electrically coupled to the implantable medical device 714 usingany suitable technique or combination of techniques.

All references and publications cited herein are expressly incorporatedherein by reference in their entirety into this disclosure, except tothe extent they may directly contradict this disclosure. Illustrativeembodiments of this disclosure are discussed and reference has been madeto possible variations within the scope of this disclosure. These andother variations and modifications in the disclosure will be apparent tothose skilled in the art without departing from the scope of thedisclosure, and it should be understood that this disclosure is notlimited to the illustrative embodiments set forth herein. Accordingly,the disclosure is to be limited only by the claims provided below.

What is claimed is:
 1. A power converter comprising: first and secondelectrodes; a three-dimensional current collector disposed between thefirst and second electrodes and electrically coupled to the firstelectrode; a charge carrier separator disposed on at least a portion ofa surface of the three-dimensional current collector; a hole conductorlayer disposed on at least a portion of the charge carrier separator andelectrically coupled to the second electrode; a counter electrodedisposed between the hole conductor layer and the second electrode andelectrically coupling the hole conductor layer and the second electrode;and nuclear radiation-emitting material disposed such that at least onenuclear radiation particle emitted by the nuclear radiation-emittingmaterial is incident upon the charge carrier separator, wherein thenuclear radiation-emitting material is disposed in a matrix adjacent tothe counter electrode such that the counter electrode is disposedbetween at least a portion of the nuclear radiation-emitting materialand the charge carrier separator; wherein the charge carrier separatoris adapted to separate electron-hole pairs generated in the chargecarrier separator by impact of the at least one nuclearradiation-emitting particle on the charge carrier separator.
 2. Thepower converter of claim 1, wherein the nuclear radiation-emittingmaterial and matrix are disposed on the counter electrode.
 3. The powerconverter of claim 1, wherein the matrix comprises a polymer.
 4. Thepower converter of claim 3, wherein the polymer comprises a paraffin. 5.The power converter of claim 1, wherein the matrix comprises a liquid.6. The power converter of claim 1, wherein the matrix comprises at leastone of a metal or an oxide.
 7. The power converter of claim 1, whereinthe counter electrode is electrically coupled to the second electrodewith a conductive adhesive.
 8. The power converter of claim 1, whereinat least a portion of the nuclear radiation-emitting material comprisestritium.
 9. The power converter of claim 1, wherein at least a portionof the charge carrier separator comprises quantum dots.
 10. The powerconverter of claim 1, wherein the three-dimensional current collectorcomprises a porous Ti/TiO₂ material.
 11. The power converter of claim 1,wherein the hole conductor layer comprises a p-type semiconductormaterial comprising CuSCN.
 12. The power converter of claim 1, whereinthe charge carrier separator comprises a first material and a secondmaterial.
 13. The power converter of claim 12, wherein the firstmaterial is disposed on the at least a portion of the surface of thethree-dimensional current collector and the second material is disposedon at least a portion of the first material.
 14. The power converter ofclaim 13, wherein the first material comprises an oxide and the secondmaterial comprises quantum dots.
 15. An implantable medical devicecomprising the power converter of claim
 1. 16. The power converter ofclaim 1, wherein the hole conductor layer comprises a p-typesemiconductor material.
 17. The power converter of claim 16, wherein thep-type semiconductor material comprises PTAA (poly(triaryl amine).